Http MIDlet : Networks « J2ME « Java
Http MIDlet
/*
J2ME in a Nutshell
By Kim Topley
ISBN: 0-596-00253-X
*/
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.AlertType;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.StringItem;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
public class HttpMIDlet extends MIDlet
implements CommandListener, Runnable {
private Display display;
private Form addressForm;
private Form connectForm;
private Form displayForm;
private TextField serverURL;
private StringItem messageLabel;
private StringItem errorLabel;
private Command okCommand;
private Command exitCommand;
private Command backCommand;
protected void startApp() throws MIDletStateChangeException {
if (display == null) {
initialize();
display.setCurrent(addressForm);
}
}
protected void pauseApp() {
}
protected void destroyApp(boolean unconditional)
throws MIDletStateChangeException {
}
public void commandAction(Command cmd, Displayable d) {
if (cmd == okCommand) {
Thread t = new Thread(this);
t.start();
display.setCurrent(connectForm);
} else if (cmd == backCommand) {
display.setCurrent(addressForm);
} else if (cmd == exitCommand) {
try {
destroyApp(true);
} catch (MIDletStateChangeException ex) {
}
notifyDestroyed();
}
}
public void run() {
InputStream is = null;
HttpConnection conn = null;
try {
String url = serverURL.getString();
if (!url.startsWith("http://") &&
!url.startsWith("https://")) {
url = "http://" + url;
}
conn = (HttpConnection)Connector.open(url, Connector.READ_WRITE);
} catch (Exception ex) {
System.out.println(ex);
ex.printStackTrace();
Alert alert = new Alert("Invalid Address",
"The supplied address is invalid\n" +
"Please correct it and try again.", null,
AlertType.ERROR);
alert.setTimeout(Alert.FOREVER);
display.setCurrent(alert, addressForm);
return;
}
try {
// Fetch the required page, reading up
// to a maximum of 128 bytes
if (conn.getResponseCode() == HttpConnection.HTTP_OK) {
is = conn.openInputStream();
final int MAX_LENGTH = 128;
byte[] buf = new byte[MAX_LENGTH];
int total = 0;
while (total < MAX_LENGTH) {
int count = is.read(buf, total, MAX_LENGTH - total);
if (count < 0) {
break;
}
total += count;
}
is.close();
String reply = new String(buf, 0, total);
messageLabel.setText(reply);
} else {
messageLabel.setText("Failed: error " + conn.getResponseCode() +
"\n" + conn.getResponseMessage());
}
// Get the response code and print all the headers
System.out.println("Response code = " + conn.getResponseCode());
System.out.println("Response message = " + conn.getResponseMessage());
for (int i = 0; ; i++) {
String key = conn.getHeaderFieldKey(i);
String value = conn.getHeaderField(i);
if (key == null) {
// Reached last header
break;
}
System.out.println(key + " = " + value);
}
conn.close();
display.setCurrent(displayForm);
} catch (IOException ex) {
System.out.println(ex);
ex.printStackTrace();
Alert alert = new Alert("I/O Error",
"An error occurred while communicating with the server.",
null, AlertType.ERROR);
alert.setTimeout(Alert.FOREVER);
display.setCurrent(alert, addressForm);
return;
} finally {
// Close open streams
try {
if (is != null) {
is.close();
is = null;
}
} catch (IOException ex1) {
}
try {
if (conn != null) {
conn.close();
conn = null;
}
} catch (IOException ex1) {
}
}
}
private void initialize() {
display = Display.getDisplay(this);
// Commands
exitCommand = new Command("Exit", Command.EXIT, 0);
okCommand = new Command("OK", Command.OK, 0);
backCommand = new Command("Back", Command.BACK, 0);
// The address form
addressForm = new Form("HTTP Client");
serverURL = new TextField("URL:", "", 256, TextField.ANY);
addressForm.append(serverURL);
addressForm.addCommand(okCommand);
addressForm.addCommand(exitCommand);
addressForm.setCommandListener(this);
// The connect form
connectForm = new Form("Connecting");
messageLabel = new StringItem(null, "Connecting...\nPlease wait.");
connectForm.append(messageLabel);
connectForm.addCommand(backCommand);
connectForm.setCommandListener(this);
// The display form
displayForm = new Form("Server Reply");
messageLabel = new StringItem(null, null);
displayForm.append(messageLabel);
displayForm.addCommand(backCommand);
displayForm.setCommandListener(this);
}
}
